Self-reinforced plastic hose and method for molding same

ABSTRACT

The hose of the present invention comprises an all plastic multilayer hose having a reinforcement therein which is of a material which is flexible and stiff under normal working conditions and which has a flow temperature less than the flow temperature of the cover and liner layers and which forms spaced reinforcing elements incident to the manufacture of the hose. The present invention contemplates use of an apparatus and simplified method which permits the reinforced hose to be readily manufactured in predetermined lengths or continuously so as to provide a hose of indefinite lengths.

United States Patent 1191 Roberts Mar. 25, 1975 1 1 SELF-REINFORCED PLASTIC HOSE AND METHOD FOR MOLDING SAME [75] Inventor: Robert E. Roberts, Wilton, Conn.

[73] Assignee: Fred T. Roberts & Company,

Wilton, Conn.

[22] Filed: Feb. 7, 1974 [21] Appl. No.: 440,458

Related U.S. Application Data [63] Continuation of Ser. Nos. 248,932, May 1, 1972, abandoned, and Ser. No. 41,796, June 1, 1970,

abandoned.

[52] U.S. C1 138/121, 138/129, 264/99, 264/173, 264/209, 264/290, 264/314, 264/D1G. 52 1 [51] Int. Cl. B296 17/07, F16] 11/08 [58] Field 01 Search 264/89, 90, 92, 93, 94,

[561 References Cited UNITED STATES PATENTS 2,897,840 8/1959 Roberts et a1. 264/94 X 3,235,440 2/1966 Gould 156/209 X 3,256,131 6/1966 Koch et al. 161/119 3,510,388

5/1970 Hunt et a1 161/119 Primary Examiner-Jan H. Silbaugh Attorney, Agent, or Firm-Thomas L. Tully; Arthur A. Johnson 5 7] ABSTRACT The hose of the present invention comprises an all plastic multilayer hose having a reinforcement therein which is of a material which is flexible and stiff under normal working conditions and which has a flow temperature less than the flow temperature of the cover and liner layers and which forms spaced reinforcing elements incident to the manufacture of the hose. The present invention contemplates use of an apparatus and simplified method which permits the reinforced hose to be readily manufactured in predetermined lengths or continuously so as to provide a hose of indefinite lengths.

7 Claims, 9 Drawing Figures PMENTED 3,872,893

SHEET 3 o 3 k mw MP, M W K b, m. w \nmmd m. mw mm W x W llllllillllllnlll Illlll ||||l||i|||||| m NN SELF-REINFORCED PLASTIC HOSE AND METHOD FOR MOLDING SAME This is a continuation of applications -Ser. Nos. 248,932, filed May I, 1972, and 41,796, filed June 1, 1970, both now abandoned.

Heretofore, flexible hose was made by incorporating a wire spring coil reinforcement between the cover and liner layers. This wire spring had to be prefabricated and assembled with the liner layers and cover layers is predetermined spaced relation so as to provide spaced reinforcements. This normally was used to provide hose of predetermined lengths due to the limitations in connection with the forming of the reinforcing spring and the placing of the spring in the hose.

The present invention overcomes these difficulties by providing a simplified method and apparatus for producing a hose construction in which the hose is formed of an all plastic material and has a reinforcement which is formed in predetermined spaced relation within the hose as an incident to the manufacture of the hose so that hose of predetermined lengths or indefinite lengths can be readily manufactured.

This is accomplished by providing a tube of elastomeric material, said tube having at least a cover layer and a liner layer with an intermediate layer of thermoflowable' reinforcing material. The tube is assembled in the corrugated cavities of a heated mold and is of such a character that the reinforcing layer has a flow point or temperature less than the flow temperature of the cover and liner layers, and, when heated in a mold to a temperature which is above the flow temperature of the reinforcing layer and below the flow temperatures of the cover and liner layers and pressed against the corrugated mold, will cause the reinforcing layer to flow into the corrugations of the mold and the cover and liner layers adhere together adjacent the crests of the corrugations of the mold, thus producing spaced reinforcements accurately located along the hose. The hose is set in molded form and removed from the mold.

In accordance with the present invention the tube can be made in a triple extruder in which the three layers are superposed to form the tube which is inserted into a suitable mold to ultimately mold the hose.

By the novel method of the present invention, the all plastic hose having spaced reinforcements is formed as an incident to and in a single molding operation, thus greatly reducing the cost of making the hose and increasing the accuracy of the reinforcement.

Other features and advantages of the invention will be apparent from the specification and claims when considered in connection with the accompanying drawings in which:

FIG. 1 is a fragmentary sectional view showing the tube inserted in a mold.

FIG. 2 is a view similar to FIG. 1 with internal pressure on the tube starting the flow of the heated reinforcing layer.

FIG. 5 diagrammatically shows the apparatus for making continuous hose.

FIG. 6 is a sectional view through the extruder heads t ke sla Iir 9..6. Qt F 91 5-,

FIGS. 7 and 8 are fragmentary sectional views of the molds at the left end of the machine of FIG. 5 receiving and.m9 s 2s. tb91a 2e 29.2 beset-..

FIG. 9 is a fragmentary sectional view ofthe end of the fixed mandrel at the end of the molding operation.

The hose of the present invention comprises an all plastic, flexible, molded, corrugated hose of elastomeric material which includes a tube 10 or tubular member which incudes at least three elementsan inner layer 11, an outer or cover layer 12 and a reinforcing layer 13, which reinforcing layer comprises spaced resilient stiff reinforcements for the hose disposed between the inner layer and cover layer. These materials can be thermosetting, thermoplastic-or combinations of said materials provided said materials are compatible and the flow point of the reinforcing material, i.e., a temperature at which the material of the reinforcing layer readily flows under molding pressure, is substantially lower than the flow point of the inner and cover layers, and the material of the reinforcements being such that it is stiff and resilient in normal operating temperatures of the hose. Should additional protective layers be required for the inner layer or cover layer, this can be applied without changing the present invention.

In an example of the present invention a tube would have an inner layer and a cover layerof flexible grades of polyvinyl chloride having a flow point of 385 and a reinforcing layer of polyvinyl chloride of a relatively rigid grade having a flow point of 350. (All temperatures noted herein are in degrees Fahrenheit). The tube is molded at a temperature above the flow point of the reinforcing layer and below the flow point. of the inner and outer layers, at about 370. At this temperature the inner and cover layers stretch to conform to the mold and the reinforcing layers becomes flowable and flows into the corrugations in the mold] to produce between the inner and cover layers accurately spaced and uniform reinforcing elements which are resilient and stiff at temperatures of normal use for the hose.

In another example the reinforcing layer could be of a reclaimed rubber which, when set up, has a Shore hardness ofabout 70 or more, and the inner layer could be of neoprene and the cover layer could be of butyl or neoprene which, when set up, have a Shore hardness of about 50 and the materials of each layer comply with the flow point requirements for said layer. The molding temperature would be between the flow point for the layers. Other combinations showing flow points and molding temperatures are as follows:

Reinforcing Inner Molding Outer Layer Layer Layer Temp.

Polyethylene 400 Polystyrene 350 Chlorinated polyester 430 375 Polyethylene 550 Polypropylene 470 Polyethylene 550 500 Polyethylene 450 ABS 400 Polyethylene 450 425 PVC 385 Nylon 347 PVC 385 360 Chlorinated polyester 390 PVC 350 Styrene hutadiene 400 375 -Continued V M I Reinforcing Inner Molding Outer Layer Layer Layer Temp.

PVC 385 Acctal copolymcr "M W 360 PVC 3x5 370 Styrcne butadienc 300 Urca amino 260 Polyethylene 300 275 Styrene butadicnc 4l0 PVC/ABS 390 Styrene butatlicnc 410 400 An advantage of the invention resides in the fact that intoasecond layer over the inner layer, and the combithe spaced reinforcements of the reinforcing layer are nation is fed through a third extrusion head 33 which formed as an incident to the molding of the hose and extrudes the outer layer 12. this reduces the handling required in the manufacture The tube 10 ofconcentric layers is fed along the fixed of the hose. mandrel or core 30 and onto the molding extension 38 In accordance with the present invention the tube 10 secured to the end of the fixed mandrel and which excomprises the three basic layersthe inner layer 11, tends into the molding area. The end of the core carries the outer layer 12 and the intermediate or reinforcing a head 39 having passages 40 to permit the injection of layer 13. As shown in FIG. 1, the tube is inserted into molding pressure within the heated tube to cause the a cavity 14 of a multipart heated mold 15, 15a having tube to be expanded outwardly progressively, as shown a corrugated wall 16 in the cavity and pressure is ap- 20 in FIGS. 5, 7 and 8, where it is completely molded. If plied to the interior of the heated tube to cause the madesired, a valve 41 on the end of the extension (FIG. terial of the tube to be pressed outwardly against the 9) seals off the pressure and the ports 42 and bore 43 corrugated wall. While an expanding mandrel or an air provide a return flow for the pressure medium. bag may be used, as herein illustrated the pressure fluid The molded tube continues as a molded hose with the is applied directly into the interior of the tube. It will a ed reinforcing elements, through the curing station be noted that the cover layer and the inner layer which a d the s t hose is discharged at the other end of the are moved toward one another under this action by the l d loops f th lds as sh wn in FIG. 5. crests of the corrugations of the wall and bonded to- Th di h g d h can be stored in any suitable gether will cause the flowable material of the reinforca r a d the r uired length of hose removed thereing layer to move to form reinforcing elements accuf when desir d, rately located in the corrugations of the hose. It will be s n from the foregoing that the present 3 ShOWS the finished molded hose With the Telflnovel invention in a single molding operation provides forcemeht material being disposed in the Spaced P an all plastic corrugated flexible hose of elastomeric tiohs in the corrugations and the Cover and inner layer material having spaced reinforcing elements therein ac- Secttred together at the troughs of the molded hosecurately located with respect to the corrugations and The hose is then Set in its molded Condition and is capable ofserving as reinforcements for the hose under thereafterremoved from the mold. If the material is normal temperatures f thermosetting, it is heated for a sufficient time to comvariations and difi ti may be d i i h P y set or Cure the hose before It is Cooled and scope of the claims and portions of the improvements moved from the mold and if it is thermoplastic the hose may b d i h h is cooled to set it in its molded form before the hose is 1 l i v removed from t mhldl. The method of making a self-reinforced corru- In cases where the hose is made of a predetermined gated hose of thermoformable elastomeric material length'and it is desired tomolcl a mounting sleeve intewithout the necessity of incorporating non-elastomeric gral there th. this 011 be accompli hed y 1 P ug 20 reinforcement materials comprising the steps of'forminserted in the end ofthe tube, as shown in FIG. 4, and ing'a tubular member by extruding an inner tubular cooperating with the cylindrical end section 21 of the layer consisting essentially of elastomeric material, exmold to produce the cylindrical mounting sleeve on the truding a tubular reinforcing layer consisting essentially hose. It will be noted that the excess of the reinforcing of elastomeric material over said inner layer, and exmaterial is permitted to flow out and into the recesses truding a tubular cover layer consisting essentially of 22when it becomes flowable under the molding heat. elastomeric material over said reinforcing layer, the

If desired, the present invention is capable of producmaterial ofthe reinforcing layer having a flow temperaing molded hose in indefinite lengths. An apparatus for ture lower than the material of the inner layer and the accomplishing this is diagrammatically shown in FIG. cover layer, inserting said tubular member into a mold 5 in which a fixed core or mandrel 30 passes through having a cavity provided with a corrugated wall, heatthree extrusion heads 31, 32, 33 and into a molding ing said tubular member to a molding temperature unit disposed in a heating station 34 and a curing staabove the flow temperature of the reinforcing layer and tion 35 shown diagrammatically. The molding unit lower tha nthe flow temperature of the inner layer and Compr ses a P ir Of pp conveyors each the cover layer, applying internal pressure to the tubuhaving a plurality of mold Sections 37, pref ra ly lar member to force the cover layer of the tubular hinged together as shown at H in FIG. 7 and movable member into conforming engagement with the corruin closed paths in the directions of arrow A (FIG. 5) gated mold wall to mold the exterior of the hose, said into cooperating molding relation about the tube to pressure being sufficient to cause portions of the flowmOve therewith as it emerges frOm the e ruder. able reinforcing layer to be displaced into the troughs In the illustrated form of the invention an extrusion head 31 extrudes the'inner layer 11 on the mandrel, which layer moves through the second extrusion head 32 which extrudes the layer 13 of reinforcing material in the cover layer produced by the corrugations of the mold, and to cause the cover layer and inner layer to engage and adhere together over the crests of the cor- "in a single molding operation, said reinforcing layer forming accurately and uniformly spaced resilient reinforcing portions conforming to the corrugations of the mold and disposed between said inner layer and saidcoveulayer.

2. The method according to claim 1 in Which said tubular member is formed by extruding said inner tubular layer, said tubular reinforcing layer and said tubular cover layer in a triple extruder.

3. The method according to claim 1 in which each of said layers consists essentially of a polyvinyl chloride elastomer.

duced according to the method of claim 2. 

1. The method of making a self-reinforced corrugated hose of thermoformable elastomeric material without the necessity of incorporating non-elastomeric reinforcement materials comprising the steps of forming a tubular member by extruding an inner tubular layer consisting essentially of elastomeric material, extruding a tubular reinforcing layer consisting essentially of elastomeric material over said inner layer, and extruding a tubular cover layer consisting essentially of elastomeric material over said reinforcing layer, the material of the reinforcing layer having a flow temperature lower than the material of the inner layer and the cover layer, inserting said tubular member into a mold having a cavity provided with a corrugated wall, heating said tubular member to a molding temperature above the flow temperature of the reinforcing layer and lower than the flowtemperature of the inner layer and the cover layer, applying internal pressure to the tubular member to force the cover layer of the tubular member into conforming engagement with the corrugated mold wall to mold the exterior of the hose, said pressure being sufficient to cause portions of the flowable reinforcing layer to be displaced into the troughs in the cover layer produced by the corrugations of the mold, and to cause the cover layer and inner layer to engage and adhere together over the crests of the corrugations of the mold, and setting the hose as molded in a single mold operation, said reinforcing layer forming accurately and uniformly spaced resilient reinforcing portions conforming to the corrugations of the mold and disposed between said inner layer and said cover layer.
 2. The method according to claim 1 in which said tubular member is formed by extruding said inner tubular layer, said tubular reinforcing layer and said tubular cover layer in a triple extruder.
 3. The method according to claim 1 in which each of said layers consists essentially of a polyvinyl chloride elastomer.
 4. The method according to claim 3 in which said molding temperature is about 370* F.
 5. A continuous molding method according to claim 1 in which reinforced corrugated hose of continuous length is molded and subsequently cut into hoses having the desired lengths.
 6. A self-reinforced, extruded, corrugated hose produced according to the method of claim
 1. 7. A self-reinforced, extruded, corrugated hose produced according to the method of claim
 2. 